High-purity hydrogen was produced by catalytic steam reforming of coke oven gas (COG) in a fluidized bed membrane reactor (FBMR), assisted by calcined dolomite and a tubular palladium membrane. This membrane-assisted and sorption-enhanced steam-COG reforming process was denoted as MA-SE-SRCOG. A novel bimetallic Ni–Fe/mayenite (Ca12Al14O33) catalyst was first tested in a fixed bed reactor and was then applied to steam reforming of COG in the pilot-scale FBMR. The Ni-0.1Fe/mayenite catalyst showed good sulfur tolerance during steam reforming of COG, and no carbon deposition was detected on the catalyst surface. Partial substitution of “free oxygens” in Ca12Al14O33 by sulfur to form Ca12Al14O32S was observed by XRD characterization. With hydrogen being separated by palladium membrane and CO2 being captured by calcined dolomite, a hydrogen recovery efficiency > 1.7 along with a CH4 conversion of 0.93 and near-zero CO selectivity was achieved by steam reforming of COG at 560 °C, S/C = 4 in the FBMR. Initial CO and H2 contents suppressed conversion of CH4 during steam reforming of COG at specific operating temperature, and restrictions from initial CO were more serious than initial H2. MA-SE-SRCOG efficiently overcame the restrictions of initial CO and H2 and was able to produce over 4.0-fold H2 from COG. A hydrogen permeation flux of 2.14 × 10–2–3.34 × 10–2 mol/m2·s having a purity of >99.9 vol % (with deletion of N2) was obtained at the permeation side. Excessive steam (S/C > 4) was observed to decrease CH4 conversion, which could be ascribed to the decreased residence time of reactants and increased bypassing of reactants through large voids in the reactor at a high S/C ratio. Over high concentration of steam in the reactor side also inhibited permeation of H2. Strong attachment of filler particles on the Pd membrane surface was detected by EPMA analysis, but no metal contents from the catalyst/sorbent were found inside the Pd layer yet after 30 h serving in FBMR.

No abstract

No abstract

No abstract

No abstract